1. Field of the Invention
This invention relates generally to the monitoring of pressure, and is more particularly concerned with pressure monitoring and display means for the air tank of a self contained breathing apparatus.
2. Discussion of the Prior Art
Self contained breathing apparatuses (SCBA) are commonly used in many hazardous environments such as fires and other smoke- or gas-filled environments. A person such as a firefighter uses an SCBA in order to enter the hazardous environment; and, one key to the ability to survive in the environment is to have an adequate supply of air. Though a person will generally enter a hazardous environment with a full tank of air, some means must be available whereby the remaining air can be monitored so the person can leave the hazardous environment before the air supply is depleted.
Conventionally, an SCBA is equipped with a pressure gauge for constantly indicating the pressure remaining in the air tank. The pressure gauge, however, is typically connected to the equipment so that the gauge is exposed to the environment. As a result, when there is, e.g., heavy smoke, the person is unable to see the gauge clearly. There have been efforts at providing a light display so the person using an SCBA constantly has the light display within the field of vision, the light display indicating the pressure remaining in the air tank. The light display, however, has also been exposed to the environment, so it is subject to damage by a hot and/or corrosive environments. It is also subject to poor visibility in an environment of dense smoke or the like.
Thus, the prior art has not provided a reliable, always visible indication of air pressure for an SCBA.